The development and exploitation of alkynyliodonium salts for stereoselective organic synthesis will be pursued. These reagents display unique reactivity patterns which permit polycyclic chemical structures to be assembled readily from simple acyclic precursors. In particular, the use of nitrogen-containing addends with these salts will lead to efficient construction of the molecular framework of several pharmaceutically interesting alkaloids including members of the Cephalotaxus group, as well as agelastatin A, magellaninone, and palau'amine. Several of these target structures (e.g., deoxyharringtonine, agelastatin A) display very promising antileukemic and antineoplastic activity, while palau'amine elicits an immunomodulatory response. Timely acquisition of these bioactive targets through alkynyliodonium salt methodology will contribute to an understanding of their mechanism of action and will provide lead structures for further optimization/evaluation of biological activity.